RFR: 8343218: Disable allocating interface and abstract classes in non-class metaspace [v2]

[Coleen Phillimore]

On Wed, 30 Oct 2024 12:03:43 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Change the code to allocate all Klasses to class-metaspace until c2 dependencies are understood and fixed, and more urgent need arises when compressing klass pointers to smaller numbers of bits.
>> Tested with tier1-4.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update src/hotspot/share/oops/instanceKlass.cpp
>   
>   Co-authored-by: David Holmes <62092539+dholmes-ora at users.noreply.github.com>

I don't see any evidence of c1 unsafely assuming that a Klass pointer can be encoded and decoded.  Since the parent CR for this bug is being fixed to add asserts for safety in C2 [JDK-8343206](https://bugs.openjdk.org/browse/JDK-8343206), I'm closing this as WNF.

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PR Comment: https://git.openjdk.org/jdk/pull/21769#issuecomment-2452277358